Breech mechanism for firearms



April 14 1931- J. M. BRowNlNG 1,801,070

BREECH MECHANISM FOR FIREARMS Fild June 12. 1929 Patented rpr. ld, 1931 @AEE JOI-le- Iv. BRO'WNING, DECEASED, LATE OF OGDEN, UTAH, BY JOHN BROWNIGG, AD-

IETSTRATR, 0F OGDEI UTAH, ASSIGNOR TO J'. E. BROWNING COMPANY, OF (EG-DEN, TH, A OORPORATEON OF UTAH BRE-ECF MEGHANISM FOR FIREARMS YApplication filed June 12,

and further to provide means operative upon recoil for ireaking the toggle to permit the breech bolt to `move rearward. Such toggle link mechanisms are objectionable, as they involve the transmission of the recoil pressure through two separatelinks and through three separate pivotal connections. In accordance with tl e present invention the objections incident to the earlier mechanisms are avoided by providing a single pivoted lock link or bolt which directly engages the 'breech bolt to normallv hold it inV tiring position. `Upon recoil the lock bolt is automatically moved out of obstructive relationship with the breech bolt, there is preferably provided a connecting means between the breech bolt and the lock bolt for transmitting motion from the former to the latter. The said connecting means, however. is normally so positioned as 'to be incapable of moving the lock bolt.

ln the accompanying drawing there is shown a diagrammatic embodimentof the i vention, but it will be understood that the drawing is for illustrative purposes only and -is not to be construed as defining or limiting the scope of the., invention, the claims form` ing a part of this specifica-tion being relied upon for that purpose.

Of the drawing:

lEig. l is a plan view, largely diagrammatic, of a barrel extension, breech bolt and breech mechanism embodying the invention.

Fig. 2 is a side view of the parts shown in Fig. l, the said parts being shown in their forward firing positions.

yFig. 3 is a view similar to Fig. 2, butshowing the parts moved rearward to theLposit-ion 1929. sei-iai No. 370,324.

where the unlocking action of the breech mechanism begins` Fig. l is ak View similar to Fig-2, but showing the .parts in intermediate positions.

Fig. 5 is a view similar to Fig. 2, but showing the parts in the positions of complete recoil.

Referring to the drawing, l represents a breech slide or bolt which normally closes the rear end of the barrel 2 as shown in Figs. l and 2, but which is movable rearward relatively to the barrel during the recoil action of the firearm. There is also provided a barrel extension 3 which 'is connected with the barrel 2, the said barrel extension and barrel preferably being movable rearward to a limited extent upon recoil following the discharge of the firearm. The breech bolt l is. suitably guided between the side walls 4:, 4 of the barrel extension 3 for rearward movement as stated, losingV provided at its sides w'th tongues 5, which enter grooves 6, 6 in the said side walls. v

l The `breech bolt l is normally held in its forward locked position by means of a locking bolt .7 which is pivotally mounted 'at the rear thereof for movement about a transverse horizontal axis. ylfhis pivotal axis is ipreferably out ofthe oath of rearward movement of the breechbolt. llhen the barrel eX- tension and breech bolt are both movable rearward, as is preferred, the bolt 7 1s pivoted to the barrel extenslon. As shown there is a transverse 'pivot pin 8 which extends through the bolt and through the side walls ll, l of the barrelextension. Y i

Vlhen the parts are in normal positions as shown in Fig. 2, the breech bolt T directly engages at its front with the rear end of the breech bolt at 9 and serves to firmly lock the breech bolt against rearward movement relatively to the barrel extension. The rearward thrust on the breech bolt, resulting from the discharge of the firearm, is transmitted directly to the lock bolt. This thrust maybe taken entirely upon the pivot pin 8, but it is usually desi'rableto provide additional -means for taking a part of the thrust and for thus assisting in resisting the rearward pressure exerted on the lock bolt by the breech bolt.

preferably concentric with the pivotal axisY of the bolt at 8.

Preferably, the engaging surfaces of the lock bolt 7 and the breech bolt 1, as shown at 9 in Fig. 2, are not concentric with the pivotal axis at 8, but are at a slight angle to a concentric are as clearly indicated. Thus when the lock bolt is moved downward, there is a wedging action between the surfaces at 9 and the concentric surface on the abutment 10. This wedging action serves to force the breech bolt forward Yto its veX- treme position and further serves to limit downward movement of the lock bolt. Should this wedging action fail, by reason of wear or otherwise. to limit the downward movement of the lock bo-lt, a shoulder 12 on the said bolt is positioned to engage the upper surface of the abutment 10 and thus positively limit the movement.

There is provided a connecting means between the breech bolt and the lock bolt whichV is normally inoperative, but which upon recoil automatically becomes operative to pivotally move the-lock bolt out of its locking or obstructive relationship with the breech bolt. Preferably this connecti means is a link13 pivotally connected wi n the breech bolt 1-with the lock bolt 7. VThis link 13 is preferably centrally located, being pivoted to the breech bolt 1 by means of a pivot pin at 111 and being pivoted to the lock bolt 7A by means of a pivotpin at 15. At least one of the link bearings, as for instance that at 15, has sufficient play to prevent the transmission of any pressure tliroughrthe said link 13 when the parts are in normal position, the construction being intentionally such that all pressure will be transmitted directly through the engaging surfaces at 9 as already described. Y

There is provided a suitable means op'- erative upon recoil to render the connecting means operative for the purpose described. `When the said means is a link' such as 13,

the said link is automatically moved about its `pivotal connection with the breech bolt to a position enabling it to transmit pressure fromr the breech bolt to the lock bolt so as to move the latter out of its obstructive relationship. W hen the connecting link and lock bolt are pivotally connected with each other as shown. thisy upward movement of the connecting link may be effected by giving the lock bolt an initial upward movement toward a position outof its locking or obstructive relationship with the breech bolt 1. lt will be obvious from an inspection of Fig. lthat as soon as the lock bolt has been swung upward to a slight extent, the angular position of the operating link 13 is changed and that any lost motion in the bearings of the sait link 13 is taken up. The recoil action of the breech bolt is then transmitted through the link 13 to move or at least assist in moving the lock bolt to a position entirely out of the path of the breech bolt as shown in Fig. 5.

W hen the barrel and barrel extension move rearward to a limited extent upon recoil, as is preferred, advantage is taken of this movement to relatively move the lock bolt to effeet unlockinfr. The particular means whereby this result is obtained may be varied but as shown the lock bolt is provided with a rearward extension or arm 16 carrying a transverse bearing pin 17 on which are mounted rollers 18, 18. Two 'cam plates 19, 19 are 'provided in relatively lined positions on the main frame of the firearm, and each of these two plates 19, 19 is provided with a cam surface 2O in position for engagement by the corresponding roller.

Preferably there is an initial combined rearward movement of the barrel extension and breech bolt in fixed relationship with each other, the parts moving rearward from the position shown in Fig. 2 to the position shown in Fig. 3. As soon asthe position shown in Fig. 3 is reached, the rollers 18, 18 engage the cam surfaces at 20 and the lock bolt is forced-to turn in the clockwise direction, the rear arm 16 thereof moving downward andthe front end moving upward.y As the front end of the lock bolt moves upward, the angular position ofv the operating link 13 is changed, and thereupon the recoil action of the breech bolt is transmitted through theV direction, the partsv finally reaching the rela-` tive positions as shown in Fig. 5 which is the fully recoiled position. 1t will be observed that the arm 16 engages the bottom of the abutment 10 to prevent any relative movement beyond the position shown in Fig'. 5. l

1n accordance with customary practice, the breech bolt properly biased, as forv instance by a spring (not shown), for forward return movement to its normal locked position as shown in Fig. 1. Tt will be uiiderstoody that during return movement the motions heretofore described are reversed, the

parts passing through the position shown in Fig. 1, then through the position shown in Fig. 3 and' finally reaching the Vposition.

shown in Fig. 2. y

VVlfhat is claimed is:

` 1. In a breech mechanism for a firearm, the combination of a' breech bolt movable rearward upon recoil, a lock bolt pivoted behind the breech bolt and normally directly engagingthe breech bolt to obstruct rearward movement, means operative upon recoil to initially move' the lock bolt about its pivot toward Va position out of obstructive relationship with the breech bolt` and-a connecting means operative after the said initialmovement of the lock bolt and serving as the result of the recoil action ot the breech bolt to continue `the said movement of the Vlock bolt.

2. lin-a breech mechanism-for a firearm,

the combination of a breech bolt movable rearward upon recoil, a lock bolt pivoted behind the breech bolt-and normally directly .engaging the breech bolt to `obstruct rearward movement, a connectinglink pivotally Vconnected with the lock bolt and the breech bolt respectively `and normally inoperative to pivotally move thelock bolt as the result oi rearward pressure transmitted from the breech bolt, and means operative upon `recoil to move ythe connecting link about its pivotal connection with the :breech bolt to a position enabling` it ito move the lool; bolt out of obstructive Arelationship with the breech bolt.

3. In a breech `mechanism for a firearm,

vthe combination `of -a breech `bolt movable rearward upon recoil, a lock bolt pivoted behind therbreech bolt and normally directly engaging the breeclybolt'to obstruct rearward movement, a connecting linl `pivotally lconnected with the loch bolt andthe breechbolt respectively and normally inoperative to pivotally move the 4loch bolt `as the result of rearward pressure transmitted from fthe breech bolt, and kmeans operative `upon vrecoil to initially move the lool; bolt about its pivot toward a position out of obstructive :relationship with the breech `bolt and .to thus move the connecting .link to a position enabling it lto continue the said movementof ithe lock fbolt as the result `of :the `recoil laction of the breech bolt.

4. In a breech mechanism for a irearm,

@the .combination lof a breech `bolt movable ative `after the said initial movement of `the lock bolt and serving as .the result of the recoil action of the breech bolt to continue `the said movement of the lockbolt to a position permitting the `rear portion of the breech bolt to move `rearward beyond the said `pivotal axis.

5. In a-breecli mechanism ffor `a iii-carni, the combination of a breech bolt movable rearward upon recoil, a pivoted loclr bolt normally directly engaging the breech bolt to obstruct rearward movement, the pivotal airis of the locklbolt being behind the nor- Amal position'oi';1 the breech bolt and below the path of rearward movement thereof,

-means operative upon recoil to initially move `the lock bolt upward about its pivot toward a position .out of obstructive relationship with the breech bolt, and a connecting means operativeV after the said initial movement of the lock bolt and serving as the result of the recoil action oi"- the breech bolt to-continue the said movement of the lock bolt upward and rearward to a position permittingthe rear portion of the breech bolt to move rearward beyond the said pivotal axis.

6. In abreech mechanism for a "irearm, 1 the combination lof a breech bolt movable rearward upon recoil, a lock bolt pivotedbehind the breech bolt and normally directly engaging the 4breech bolt to obstruct rearward movement, an abutment mounted in lined relation'to the axis of thelloclcbolt pivot and engaging a shoulder on theloclr bolt to yresist rearwardipressure on the said lock bolt,

means operative upon recoil to initially move the lock bolt about its pivot toward `position out of obstructive relationship with thebreech bolt and out of engagement with the abutment, and a connecting means operative after the said initial movement of .the lock bolt and serving as the `result of the recoil action ofthe breech bolt to continue thesaidlmovement-of the lock bolt.

J. In a breech mechanism for a lfirearm, the combination of a breech fbolt `movable rearward upon recoil, a lock bolt pivoted behind the breech'bolt and lnormally directly engaging the breech bolt to obstruct rearward movement, an abutment mounted in fixed relation to the axis of the lock `bolt pivot and engaging a shoulder on `the lock `bo'ltfto resist rearward Ipressure on the said lock bolt, a connecting link pivotally connected with i the loclr bolt and the breech bolt respectively and normally inoperative to `piv- Lll vtl llfbltntl "ilti' ora y move ie ocL oi as ie resa o rearward pressure transmitted Jfrom the breechbolt, `and 'means operativev upon recoil lto .initially movethe lock bolt about its pivot toward a position out of obstructive relationship with the breech bolt and to thus move the connecting `liiilr to a position enabling it to continue the said movement ot the lock bolt as the `result oic the recoil action or the breech bolt.

8. ln a breech mechanismfor a firearm, theV combination of a breech bolt movable rearward upon recoil, a lock-bolt pivotedbehind the breech bolt and normally directly engaging the breech bolt to obstruct rearward movement, the surfaces of engagement bebreech bolt.

tween the lock bolt and breech bolt being at an angle to an arc concentric with the axis oi lock bolt movement so to provide a wedging action as the said bolt moves into its locking position, means operative upon recoil to initially move the lock bolt about its pivot toward a position out of obstructive relationship with the breech bolt, and a connecting means operative after the said initial movement of the lock bolt and serving to continue the said movement of the lock bolt as the result ot the recoil action of the breech bolt.

9. ln a breech mechanism fora iirearm, the combination oi a barrel extension movable rearward upon recoil, a breech bolt movable rearward upon recoil, a lock bolt piv'oted to the barrel extension behind thebreech bolt and normally directly engaging the breech bolt to obstruct rearward movement thereof ative upon the combined rearward recoil 'movement of the barrel extension and breech bolt to initially move the lock bolt about its pivot toward a position out of obstructive relationship with the breech bolt, and a connecting means operative after the said initial movement ot' the lock bolt and serving as the result of the recoil action ofthe breech bolt to continue the said movement of the lock bolt.

` 10. ln a breech mechanism for a firearm, the combination of a barrel extension movable rearward upon recoil,'a. breech bolt movable rearward upon recoil, a loc-k bolt pivoted to the barrel extensionA behind the breech bolt and normally directly engaging the breech bolt to obstruct rearward movement thereof lock bolt as the result vof rearwardpressure transmitted to the link from the breech bolt, and means operative upon the combined rearward recoil movement of the barrel extension and breech bolt to move the connecting link about its pivotal connection with the breech bolt to a position enabling itto move the lock bolt out or" obstructive relationship with the 1l. ln a breech mechanism for a firearm, the combination or a barrel extension movable rearward upon recoil, a breech bolt inevable rearward upon recoil, a lock bolt pivoted to the barrel extension behind the breech bolt and normally directly engaging the breech bolt to obstruct rearward movement thereof relatively to the barrel extension, a connect'- ing link pivotally connected with the lock bolt and the breech bolt respectively and normally inoperative to pivotally move the lock bolt as the result 'of rearward-pressure transmitted to the link from the breech bolt, and means operative upon the combined rearward recoil movement of the barrel extension or the lock bolt.l

and breech bolt to initially move the lock bolt about its pivot toward a position outof obstructive relationship with the breech bolt and to thus move the connecting link to a .position enabling it to continue the said moveengaging the breech vbolt to obstruct rearward movement thereof relatively to the barrel extension, the pivotal axis of thelock bolt being behind the normal position of the breech bolt and out oi the path of rearward movement thereof, means opera-tive upon the combined rearward recoil movement of the barrel extension and breech bolt to initially Y move the lock bolt about'its pivot toward a position out of obstructive relationship with the breech bolt, and a connectine means'operative after the said initial movement of the lock bolt and servingasthe result of theM recoil action or the breech bolt to continue the said movement of the lock bolt to a position permitting the rear portion of the breech bolt to moverearward relatively to the barrel extension to a position beyond the said 55 i ioo oted to the barrel extension behind the breech bolt and normall directl `enea in the Y Y Y e g e breech bolt to obstruct rearward movement tension and engaging a shoulder kon the lock bolt to resist rearward pressure on the said lock bolt, means operative upon the combined rearward recoil movement of the barrel eX- tension and breech bolt to initially move the i lock bolt about its pivot toward apposition 'out of obstructive relationshipA with the breech bolt, and a connecting means operative after thereof relatively to the' barrel extension, an abutment iX-edly mounted on the barrel exthe said initial movement of the lock bolt and K serving as the result of the recoil action. oi the breech bolt to continue the said movement 14. ln a breechv mechanism for a firearm, the combination oit' a barrel extension movable rearward upon recoil, a. breech bolt mov-4 able rearwarduponrrecoil, a lock bolt pivoted to the barrel extension behind the breech' i bolt and normally directly engaging the breech bolt to obstruct rearward movement J'h t lt' l titl bMel t" t ereo re a ively o .ie aiiJ cir ension, an abutment liXedly mounted on the barrel eX- tension and engaging a shoulder on the lock bolt to resist rearward pressure on the said lock bolt, a. connecting link pivotally connected with the lock bolt and the breech bolt` respectively and normally inoperative to pivotally move the lock bolt as the result ot' rearward pressure transmitted to the linlr` from the breech bolt, and means operative upon the combined rearward recoil movement of the barrel extension and breech bolt to initially move the lock bolt about its pivot toward a position out of obstructive relationship with the breech boltl and to thus move the connecting link to a position enabling it to continue the said movement ot the lock bolt as the result of the recoil action of the breech bolt.

l5. In a breech mechanism for a firearm., the combination of ar barrel extension movable rearwa-rd upon recoil, a breech bolt movable rearward upon recoil, a lock bolt pivoted to the barrel extension behind the breech bolt and normally directly engaging the breech bolt to obstruct rearward movement thereof relatively to the barrel extension, an arm eX- tending rearward'from the lock bolt, means engaging said arm and operative upon the combined rearward recoil movement of the barrel extension and breech bolt to initially move the locl bolt about its pivot toward a position out of obstructive relationship with the breech bolt, and a connecting means operative after the said initial movement oi the lock bolt and serving as the result of the recoil action of the breech bolt to continue the said movement of the lool; bolt.

16. ln a breech mechanism for a firearm, tie combination ot a barrel extension movable rearward upon recoil, a breech bolt movaole rearward upon recoil, a lock bolt pivot- -ed to the barrel extension behind the breech `iolt and normally directly engaging the breech bolt to obstruct rearward movement thereof relatively to the barrel extension, a connecting link pivotally connected withthe lock bolt and the breech bolt respectively and normally inoperative to pivotally move the lock bolt as the result of rearward pressure transmitted to th-e linlr from the breech bolt, an arm extending rearward from the lock bolt, and means engaging said arm and operative upon the combined rearward recoil movement of the barrel extension and breech bolt to initially move the lock bolt about its pivot toward a position out ot' obstructive relationship with the breech bolt and to thus move the connecting link to a position enabling it to continu-e the said movement of the lock bolt as the result of the recoil action of the breech bolt.

17. ln a breech mechanism for a rearm, the combination ot a barrel extension movable rearward upon recoil, a breech bolt movable rearward upon recoil, a lock bolt Vpivoted to the barrel extension behind the breech bolt and normally directly engaging the breech bolt to obstruct rearward movement thereof relatively to the barrel extension, a cam iiX'ed against recoil movement and 'cooperative with the lock bolt upon the combined rearward recoil movement of the barrel extension and breech bolt to initially move the said bolt about its pivot toward a position out of obstructive relationship with the breech bolt and a connecting means operative after the said initial movement of the lock bolt and serving to continue the said movement of the lool; bolt as the result of the recoil action of the breech bolt.

vi8. ln a breech mechanism for a rearm, the combination of a barrel extension movable rearward upon recoil, a breech bolt movable rearward upon recoil, a lock bolt pivoted to the barrel extension behind the breech bolt and normally directly engaging the breech bolt to obstruct rearward movement thereof relatively to the barrel extension, a connecting link pivotally connected with the lock bolt and the breech bolt respectively and normally inoperative to pivotally move the lock bolt as the result of rearward pressure transmitted to the link from the breech bolt, an arm extending rearward from th loch bolt, and a cam lixed against recoil movement and cooperative with the said arm upon the combined rearward recoil movement of the barrel extension and breech bolt to initially move the said bolt about its pivot toward a position out of obstructive relationship with the breech bolt and to thus move the connecting linlr to a position enabling it to continue the said movement of the lock bolt as the result of the recoil action of the breech bolt.

In testimony whereof l have hereunto set my hand this 3l day or May, 1929.

JOHN BROWN ING,

Admm'stmtor of the State of Jom ill.

Browning, Deceased. 

